Any ideas for a Pinocchio inside-the-blue-whale backdrop?

[bobebob]

I can't think of any good ideas for a backdrop that clearly shows the scene when Pinocchio and Geppetto are in the whale's stomach or mouth or whatever? Do you guys have any decent ideas? The only thing I thought up of is cutting out a giant tonsil shape and sticking it on the roof or the wall.

Thanks in advance.